<!DOCTYPE html><html lang="zh-Hans"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1"><meta name="description" content="iOS中Class相关方法区别"><meta name="keywords" content=""><meta name="author" content="kyren"><meta name="copyright" content="kyren"><title>iOS中Class相关方法区别 | Kyren's Blog</title><link rel="shortcut icon" href="/melody-favicon.ico"><link rel="stylesheet" href="/css/index.css?version=1.9.0"><link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/font-awesome@latest/css/font-awesome.min.css?version=1.9.0"><meta name="format-detection" content="telephone=no"><meta http-equiv="x-dns-prefetch-control" content="on"><link rel="dns-prefetch" href="https://cdn.jsdelivr.net"><link rel="dns-prefetch" href="https://hm.baidu.com"><script>var _hmt = _hmt || [];
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href="#%E4%BA%8C%E3%80%81object-getClass-obj-%E4%B8%8E-obj-class-%E5%8C%BA%E5%88%AB"><span class="toc-number">2.</span> <span class="toc-text">二、object_getClass(obj)与[obj class]区别</span></a></li></ol></div></div><div class="author-info hide"><div class="author-info__avatar text-center"><img src="https://avatars.githubusercontent.com/u/5827823?v=4"></div><div class="author-info__name text-center">kyren</div><div class="author-info__description text-center">huluo的技术博客</div><div class="follow-button"><a target="_blank" rel="noopener" href="https://github.com/huluo666">Follow Me</a></div><hr><div class="author-info-articles"><a class="author-info-articles__archives article-meta" href="/archives"><span class="pull-left">文章</span><span class="pull-right">239</span></a><a class="author-info-articles__tags article-meta" href="/tags"><span class="pull-left">标签</span><span class="pull-right">41</span></a><a class="author-info-articles__categories article-meta" href="/categories"><span 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href="/categories">分类</a><a class="site-page" href="/about">关于</a></span><span class="pull-right"><a class="site-page social-icon search"><i class="fa fa-search"></i><span> 搜索</span></a></span></div><div id="post-info"><div id="post-title">iOS中Class相关方法区别</div><div id="post-meta"><time class="post-meta__date"><i class="fa fa-calendar" aria-hidden="true"></i> 2018-03-23</time></div></div></div><div class="layout" id="content-inner"><article id="post"><div class="article-container" id="post-content"><h5 id="一、isKindOfClass、isMemberOfClass和isSubclassOfClass区别"><a href="#一、isKindOfClass、isMemberOfClass和isSubclassOfClass区别" class="headerlink" title="一、isKindOfClass、isMemberOfClass和isSubclassOfClass区别"></a>一、<code>isKindOfClass</code>、<code>isMemberOfClass</code>和<code>isSubclassOfClass</code>区别</h5><figure class="highlight objectivec"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br></pre></td><td class="code"><pre><span class="line"><span class="number">1.</span>首先申明 四个类 A-&gt;B-&gt;C-&gt;D ，继承关系 A继承B,B继承C，C继承D。即D是最顶层的父类，A是最基层的子类。</span><br><span class="line">A *a = [[A alloc]init];</span><br><span class="line"><span class="number">2.</span>isKindOfClass(对象方法)</span><br><span class="line">[a  isKindOfClass:[A <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line">[a  isKindOfClass:[B <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line">[a  isKindOfClass:[C <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line">[a  isKindOfClass:[D <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line"></span><br><span class="line"><span class="number">3.</span>isMemberOfClass(对象方法)</span><br><span class="line">[a  isMemberOfClass:[A <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line">[a  isMemberOfClass:[B <span class="keyword">class</span>]]  <span class="comment">//return NO</span></span><br><span class="line">[a  isMemberOfClass:[C <span class="keyword">class</span>]]  <span class="comment">//return NO</span></span><br><span class="line">[a  isMemberOfClass:[D <span class="keyword">class</span>]]  <span class="comment">//return NO</span></span><br><span class="line"></span><br><span class="line"><span class="number">4.</span>isSubclassOfClass(类方法)</span><br><span class="line">[A  isSubclassOfClass:[A <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line">[A  isSubclassOfClass:[B <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line">[A  isSubclassOfClass:[C <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br><span class="line">[A  isSubclassOfClass:[D <span class="keyword">class</span>]]  <span class="comment">//return YES</span></span><br></pre></td></tr></table></figure>

<p>总结:isKindOfClass:确定一个对象是否是一个类的成员,或者是派生自该类的成员.(判断是否是这个类或者这个类的子类的实例)</p>
<pre><code> isMemberOfClass:确定一个对象是否是当前类的成员.(判断是否是这个类的实例)
</code></pre>
<h5 id="二、object-getClass-obj-与-obj-class-区别"><a href="#二、object-getClass-obj-与-obj-class-区别" class="headerlink" title="二、object_getClass(obj)与[obj class]区别"></a>二、<code>object_getClass(obj)</code>与<code>[obj class]</code>区别</h5><figure class="highlight objectivec"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">void</span> testClassdifference()</span><br><span class="line">&#123;</span><br><span class="line">    </span><br><span class="line">    <span class="comment">//obj为实例变量</span></span><br><span class="line">    <span class="built_in">NSObject</span> *obj = [<span class="built_in">NSObject</span> new];</span><br><span class="line">    Class cls = object_getClass(obj);</span><br><span class="line">    Class cls2 = [obj <span class="keyword">class</span>];</span><br><span class="line">    <span class="built_in">NSLog</span>(<span class="string">@&quot;实例对象：%p-%p&quot;</span> , cls,cls2); <span class="comment">//实例对象：0x107173ea8-0x107173ea8</span></span><br><span class="line">    <span class="comment">//结论：当obj为实例变量时，object_getClass(obj)与[obj class]输出结果一直，均获得isa指针，即指向类对象的指针。</span></span><br><span class="line">    </span><br><span class="line">    <span class="comment">//classObj为类对象</span></span><br><span class="line">    Class classObj = [obj <span class="keyword">class</span>];</span><br><span class="line">    Class cls3 = object_getClass(classObj);</span><br><span class="line">    Class cls4 = [classObj <span class="keyword">class</span>];</span><br><span class="line">    <span class="built_in">NSLog</span>(<span class="string">@&quot;类对象：%p-%p&quot;</span>,cls3,cls4);<span class="comment">//类对象：0x107173e58-0x107173ea8</span></span><br><span class="line">    <span class="comment">//结论：当obj为类对象时，object_getClass(obj)返回类对象中的isa指针，即指向元类对象的指针；[obj class]返回的则是其本身。</span></span><br><span class="line">    </span><br><span class="line">    </span><br><span class="line">    <span class="comment">//metaClassObj为元类对象</span></span><br><span class="line">    Class metaClassObj = object_getClass(classObj);</span><br><span class="line">    Class cls5 = object_getClass(metaClassObj);</span><br><span class="line">    Class cls6 = [metaClassObj <span class="keyword">class</span>];</span><br><span class="line">    <span class="built_in">NSLog</span>(<span class="string">@&quot;元类对象：%p-%p&quot;</span>,cls5,cls6);<span class="comment">//元类对象：0x107173e58-0x107173e58</span></span><br><span class="line"></span><br><span class="line">    <span class="comment">//结论：当obj为Metaclass（元类）对象时，object_getClass(obj)返回元类对象中的isa指针，因为元类对象的isa指针指向根类，所有返回的是根类对象的地址指针；[obj class]返回的则是其本身。</span></span><br><span class="line">    </span><br><span class="line">    <span class="comment">//rootClassObj为元类对象</span></span><br><span class="line">    Class rootClassObj = object_getClass(metaClassObj);</span><br><span class="line">    Class cls7 = object_getClass(rootClassObj);</span><br><span class="line">    Class cls8 = [rootClassObj <span class="keyword">class</span>];</span><br><span class="line">    <span class="built_in">NSLog</span>(<span class="string">@&quot;Root元类对象：%p-%p&quot;</span>,cls7,cls8);<span class="comment">//Root元类对象：0x107173e58-0x107173e58</span></span><br><span class="line">    <span class="comment">//结论：当obj为Rootclass（元类）对象时，object_getClass(obj)返回根类对象中的isa指针，因为跟类对象的isa指针指向Rootclass‘s metaclass(根元类)，即返回的是根元类的地址指针；[obj class]返回的则是其本身。因为根类的isa指针其实是指向本身的，所有根元类其实就是根类，所有输出的结果是一样的。</span></span><br><span class="line">&#125;</span><br><span class="line"></span><br><span class="line"><span class="comment">//打印信息：</span></span><br><span class="line">iOSInterview[<span class="number">8880</span>:<span class="number">1076288</span>] 实例对象：<span class="number">0x107173ea8</span><span class="number">-0x107173ea8</span></span><br><span class="line">iOSInterview[<span class="number">8880</span>:<span class="number">1076288</span>] 类对象：<span class="number">0x107173e58</span><span class="number">-0x107173ea8</span></span><br><span class="line">iOSInterview[<span class="number">8880</span>:<span class="number">1076288</span>] 元类对象：<span class="number">0x107173e58</span><span class="number">-0x107173e58</span></span><br><span class="line">iOSInterview[<span class="number">8880</span>:<span class="number">1076288</span>] Root元类对象：<span class="number">0x107173e58</span><span class="number">-0x107173e58</span></span><br></pre></td></tr></table></figure>

<p>  总：<code>object_getClass</code>(obj)返回的是obj中的isa指针；<br>  <code>[obj class]</code>则分两种情况：</p>
<ul>
<li><p>一是当obj为实例对象时，<code>[obj class]中class</code>是实例方法：- (Class)class，返回的obj对象中的isa指针,也即其本身；</p>
</li>
<li><p>二是当obj为类对象（包括元类和根类以及根元类）时，调用的是类方法：+ (Class)class，返回的结果为其本身</p>
<p>​</p>
</li>
</ul>
</div></article><div class="post-copyright"><div class="post-copyright__author"><span class="post-copyright-meta">文章作者: </span><span class="post-copyright-info"><a href="mailto:undefined">kyren</a></span></div><div class="post-copyright__type"><span class="post-copyright-meta">文章链接: </span><span class="post-copyright-info"><a href="http://huluo666.gitee.io/2018/03/23/iOS中Class相关方法区别/">http://huluo666.gitee.io/2018/03/23/iOS中Class相关方法区别/</a></span></div><div class="post-copyright__notice"><span class="post-copyright-meta">版权声明: </span><span class="post-copyright-info">本博客所有文章除特别声明外，均采用 <a target="_blank" rel="noopener" href="https://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA 4.0</a> 许可协议。转载请注明来自 <a href="http://huluo666.gitee.io">Kyren's Blog</a>！</span></div></div><div class="post-meta__tag-list"></div><nav id="pagination"><div class="prev-post pull-left"><a href="/2018/03/26/iOS%E5%A4%9A%E7%BA%BF%E7%A8%8B/"><i class="fa fa-chevron-left">  </i><span>iOS多线程</span></a></div><div class="next-post pull-right"><a href="/2018/03/22/KVO%E5%8E%9F%E7%90%86%E5%8F%8A%E5%AE%9E%E7%8E%B0/"><span>KVO原理及实现</span><i class="fa fa-chevron-right"></i></a></div></nav></div></div><footer><div class="layout" id="footer"><div class="copyright">&copy;2022 By kyren</div><div class="framework-info"><span>驱动 - </span><a target="_blank" rel="noopener" href="http://hexo.io"><span>Hexo</span></a><span class="footer-separator">|</span><span>主题 - </span><a target="_blank" rel="noopener" href="https://github.com/Molunerfinn/hexo-theme-melody"><span>Melody</span></a></div><div class="footer_custom_text">hitokoto</div><div class="busuanzi"><script async src="//busuanzi.ibruce.info/busuanzi/2.3/busuanzi.pure.mini.js"></script><span id="busuanzi_container_page_pv"><i class="fa fa-file"></i><span id="busuanzi_value_page_pv"></span><span></span></span></div></div></footer><i class="fa fa-arrow-up" id="go-up" aria-hidden="true"></i><script src="https://cdn.jsdelivr.net/npm/animejs@latest/lib/anime.min.js"></script><script src="https://cdn.jsdelivr.net/npm/jquery@latest/dist/jquery.min.js"></script><script src="https://cdn.jsdelivr.net/npm/@fancyapps/fancybox@latest/dist/jquery.fancybox.min.js"></script><script src="https://cdn.jsdelivr.net/npm/velocity-animate@latest/velocity.min.js"></script><script src="https://cdn.jsdelivr.net/npm/velocity-ui-pack@latest/velocity.ui.min.js"></script><script src="/js/utils.js?version=1.9.0"></script><script src="/js/fancybox.js?version=1.9.0"></script><script src="/js/sidebar.js?version=1.9.0"></script><script src="/js/copy.js?version=1.9.0"></script><script src="/js/fireworks.js?version=1.9.0"></script><script src="/js/transition.js?version=1.9.0"></script><script src="/js/scroll.js?version=1.9.0"></script><script src="/js/head.js?version=1.9.0"></script><script src="/js/search/local-search.js"></script><script>if(/Android|webOS|iPhone|iPod|iPad|BlackBerry/i.test(navigator.userAgent)) {
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